Prevention of induction in electric circuits



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PREVENTION OIFYINIDUGTIONIl-Nv ELECTRIC CIRCUITS. No. 355,420.A -,Pa tent;ed Jan'. 4,1887.

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UNITEn STATES PATENT Orifice.

` JOHN OSCAR STOCKWELL, BURLINGTON, KANSAS.

' PREVENTION OF INDUCTION IN ELECTRIC CIRCUITS.

SPECIFICATION forming part of Letters `Patent No. 355,420, dated January 4, 1887. Application filed Marehl, 1886. Serial No. 195,647 (No modell To all whom, it may concern,.-

Be it known that I, JOHN OSCARV STOCK- WELL, a citizen of the UnitedStates, and a resi` dent of Burlington, in the county of Coffey and State of Kansas, have invented certain new duced to s uch an extent that telephonie conversationl may not'loe interfered with at all.

The invention comprises telephones, main lines, inductorii, and details of disposition adapted to be uninfluenced by foreign sources as far as the telephonie vibrations at the telephones are concerned. K

Figure l is a general outside View of the disposition of 4the elements composing the system, while Fig. 2 is a cross-sectional view of an inductorium and of the electrical connections to the same. i

The electrical connections are not clearly shown in Fig. l, while they are in Fig. 2. Referring to the gures,it is noticed that the ele'- ments comprising` my invention are two stations, A and B, two telephones, C and4 D, one at each station, two main lines, E and F, two inductoriuins, G, with three coils to each inductorium, the outer or primary coil, H, being in circuit with the telephone, and the inner or secondary coils, I, being separately in circuit with the main lines and wound in opposite directions. Each main line has an earth-connection at each station, as shown by the squares in the lower part of Fig. l.

When telephonie communication is carried on between the two telephones any current induced from a foreign source (such as a circuit represented in part by J) in one main line will be induced in the othermain line also, and the combined result of these two induced currents upon the local circuits including the telephones will be zero, because the two coils I are wound in opposite directions.

The invention is not limited to the precise construction hcreinbefore described, as it is evident that many modifications may he made therein without departing from thespirit of the invention.

Having described my invention, what I claim is l. In a system for the prevention of induction in telephone lines, the combination at each station of an inductorium having one primary coil and two secondary coils, each primary being local and including a telephone,

and each secondary constituting a main line, y

and having an earth-connection at each station, substantially as and for the purpose described.

2. In a system for the prevention of induction in telephonelines, the combination oftwo stations, two telephones, one at each station, two main lines,A and an inductorium at each station, each having three coils,- the outer or primary coil including a telephone, and the inner or two secondary coils beingseparately in circuit with 'the'main lines and with the earth and wound in opposite directions, as and for the purpose described.

In testimony whereof I hereunto sign my name, in the presence of two subscribing witnesses, this 30th day of January, 1886.

JOHN OSCAR STOCKWELL. i 

